U.S. patent application number 15/210516 was filed with the patent office on 2017-02-23 for solar panel.
The applicant listed for this patent is SunPower Corporation. Invention is credited to Gilad ALMOGY, Nathan BECKETT, Tamir LANCE, Ratson MORAD.
Application Number | 20170054047 15/210516 |
Document ID | / |
Family ID | 58051435 |
Filed Date | 2017-02-23 |
United States Patent
Application |
20170054047 |
Kind Code |
A1 |
MORAD; Ratson ; et
al. |
February 23, 2017 |
SOLAR PANEL
Abstract
A high efficiency configuration for a solar cell module
comprises solar cells arranged in an overlapping shingled manner
and conductively bonded to each other in their overlapping regions
to form super cells, which may be arranged to efficiently use the
area of the solar module. Rear surface electrical connections
between solar cells in electrically parallel super cells provide
alternative current paths (i.e., detours) through the solar module
around damaged, shaded, or otherwise underperforming solar
cells.
Inventors: |
MORAD; Ratson; (Palo Alto,
CA) ; ALMOGY; Gilad; (Palo Alto, CA) ; LANCE;
Tamir; (Los Gatos, CA) ; BECKETT; Nathan;
(Oakland, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SunPower Corporation |
San Jose |
CA |
US |
|
|
Family ID: |
58051435 |
Appl. No.: |
15/210516 |
Filed: |
July 14, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62206667 |
Aug 18, 2015 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02S 40/34 20141201;
Y02E 10/50 20130101; H01L 31/044 20141201; Y02B 10/12 20130101;
H01L 31/0504 20130101; H02S 20/25 20141201; H02S 40/36 20141201;
Y02B 10/10 20130101; Y02E 10/547 20130101 |
International
Class: |
H01L 31/05 20060101
H01L031/05; H01L 31/02 20060101 H01L031/02; H02S 40/34 20060101
H02S040/34; H01L 31/028 20060101 H01L031/028; H01L 31/0443 20060101
H01L031/0443 |
Claims
1. A solar module comprising: a plurality of super cells arranged
in two or more physically parallel rows with the rows electrically
connected to each other in parallel, each super cell comprising a
plurality of rectangular silicon solar cells arranged in line with
long sides of adjacent silicon solar cells overlapping and
conductively bonded directly to each other to electrically connect
the silicon solar cells in series; and a plurality of detour
electrical interconnects each of which is arranged to extend
perpendicularly to the rows to electrically connect metallization
on the rear surfaces of at least one pair of equal voltage solar
cells located side-by-side in adjacent super cell rows to provide
detour current paths passing through the detour electrical
interconnect and through the rear surface metallization of the pair
of solar cells around one or more other solar cells in the event
that the one or more other solar cells provide insufficient current
for normal operation of the module; wherein the detour current
paths do not pass through bypass diodes.
2. The solar module of claim 1, wherein each detour electrical
interconnect has a length shorter than the width of two rows and is
conductively bonded at each end to one or the other of a pair of
solar cells.
3. The solar module of claim 2, wherein the detour electrical
interconnects are conductively bonded to contact pads on the rear
surfaces of the solar cells they interconnect, and the contact pads
are positioned adjacent to and elongated parallel to short ends of
their solar cells.
4. The solar module of claim 2, wherein the detour electrical
interconnects are arranged in one or more lines perpendicular to
the rows.
5. The solar module of claim 4, wherein each line of detour
electrical interconnects spans the width of the module
perpendicular to the rows and electrically interconnects all
rows.
6. The solar module of claim 1, wherein each detour electrical
interconnect extends perpendicularly to the rows to electrically
connect rear surfaces of solar cells in three or more rows.
7. The solar module of claim 6, wherein each detour electrical
interconnect spans the width of the module perpendicular to the
rows and electrically interconnects all rows.
8. The solar module of claim 1, comprising a backing sheet bonded
to a rear surface of the module, wherein the detour electrical
interconnects are provided by a planar metallization pattern on the
backing sheet.
9. The solar module of claim 8, wherein electrical connections to
bypass diodes are provided by the planar metallization pattern on
the backing sheet, the bypass diodes arranged to bypass one or more
groups of solar cells in the event that one or more solar cells in
the one or more groups provide insufficient current for normal
operation of the module.
10. The solar module of claim 8, wherein electrical connections to
a junction box are provided by the planar metallization pattern on
the backing sheet.
11. The solar module of claim 1, wherein each solar cell in the
module is electrically connected to at least one adjacent row solar
cell by a detour electrical interconnect
12. The solar module of claim 1, wherein the detour electrical
interconnects are arranged to compensate for a predetermined solar
module cracking pattern.
13. The solar module of claim 1, wherein: each detour electrical
interconnect has a length shorter than the width of two rows and is
conductively bonded at each end to one or the other of a pair of
solar cells; and each solar cell in the module is electrically
connected to at least one adjacent row solar cell by a detour
electrical interconnect;
14. The solar module of claim 1, wherein: each detour electrical
interconnect has a length shorter than the width of two rows and is
conductively bonded at each end to one or the other of a pair of
solar cells; and the detour electrical interconnects are arranged
to compensate for a predetermined solar module cracking
pattern.
15. The solar module of claim 1, wherein: each detour electrical
interconnect spans the width of the module perpendicular to the
rows and electrically interconnects all rows; and each solar cell
in the module is electrically connected to at least one adjacent
row solar cell by a detour electrical interconnect
16. The solar module of claim 1, wherein: each detour electrical
interconnect spans the width of the module perpendicular to the
rows and electrically interconnects all rows; and the detour
electrical interconnects are arranged to compensate for a
predetermined solar module cracking pattern.
17. The solar module of claim 1, comprising a backing sheet bonded
to a rear surface of the module, wherein: the detour electrical
interconnects are provided by a planar metallization pattern on the
backing sheet; and each solar cell in the module is electrically
connected to at least one adjacent row solar cell by a detour
electrical interconnect
18. The solar module of claim 1, comprising a backing sheet bonded
to a rear surface of the module, wherein: the detour electrical
interconnects are provided by a planar metallization pattern on the
backing sheet; and the detour electrical interconnects are arranged
to compensate for a predetermined solar module cracking
pattern.
19. The solar module of claim 1, further comprising bypass diodes
arranged to bypass one or more groups of solar cells in the event
that one or more solar cells in the one or more groups provide
insufficient current for normal operation of the module.
20. The solar module of claim 1, wherein the detour electrical
interconnects are conductively bonded to contact pads on the rear
surfaces of the solar cells they interconnect, and the contact pads
are positioned adjacent to and elongated parallel to short ends of
their solar cells.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of priority to U.S.
Provisional Application No. 62/206,667 titled "Solar Panel" filed
Aug. 18, 2015, which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The invention relates generally to solar cell modules in
which the solar cells are arranged in a shingled manner, and more
particularly to such solar modules in which rear surface electrical
connections between solar cells in electrically parallel rows of
solar cells provide detour current paths through the solar module
around any underperforming solar cells.
BACKGROUND
[0003] Alternate sources of energy are needed to satisfy ever
increasing world-wide energy demands. Solar energy resources are
sufficient in many geographical regions to satisfy such demands, in
part, by provision of electric power generated with solar (e.g.,
photovoltaic) cells.
SUMMARY
[0004] In one aspect, a solar module comprises a plurality of super
cells arranged in two or more physically parallel rows with the
rows electrically connected to each other in parallel. Each super
cell comprises a plurality of rectangular silicon solar cells
arranged in line with long sides of adjacent silicon solar cells
overlapping and conductively bonded directly to each other to
electrically connect the silicon solar cells in series. The solar
module also comprises a plurality of detour electrical
interconnects each of which is arranged to extend perpendicularly
to the rows of super cells to electrically connect rear surfaces of
at least one pair of solar cells located side-by-side in adjacent
rows to provide detour current paths through the module around one
or more other solar cells in the event that the one or more other
solar cells provide insufficient current for normal operation of
the module. These detour current paths do not pass through bypass
diodes.
[0005] These and other embodiments, features and advantages of the
present invention will become more apparent to those skilled in the
art when taken with reference to the following more detailed
description of the invention in conjunction with the accompanying
drawings that are first briefly described.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 shows a cross-sectional diagram of a string of
series-connected solar cells arranged in a shingled manner with the
ends of adjacent solar cells overlapping to form a shingled super
cell.
[0007] FIG. 2 shows a diagram of the front surface of an example
rectangular solar module comprising a plurality of rectangular
shingled super cells, with the long side of each super cell having
a length of approximately the full length of the long side of the
module. The super cells are arranged with their long sides parallel
to the long sides of the module.
[0008] FIGS. 3-11 show diagrams of the rear surfaces of example
solar modules in which electrical interconnections between rear
surfaces of solar cells in adjacent rows of super cells provide
alternative current paths (i.e., detours) through the solar module
around damaged, shaded, or otherwise underperforming solar
cells.
[0009] FIGS. 12A-12B show rear surface metallization of individual
solar cells and detour electrical connections between super cells
allowing current to flow around a horizontal crack in a solar
cell.
[0010] FIG. 13 shows a typical crack pattern in a conventional
solar module after uniform mechanical loading.
[0011] FIG. 14A shows an example patterned metallized back sheet
that provides electrical connections corresponding to those
provided by the electrical interconnects and return wires shown in
FIG. 10. FIG. 14B shows a close-up view of electrical
interconnections to bypass diodes in the junction box shown in FIG.
14A.
DETAILED DESCRIPTION
[0012] The following detailed description should be read with
reference to the drawings, in which identical reference numbers
refer to like elements throughout the different figures. The
drawings, which are not necessarily to scale, depict selective
embodiments and are not intended to limit the scope of the
invention. The detailed description illustrates by way of example,
not by way of limitation, the principles of the invention. This
description will clearly enable one skilled in the art to make and
use the invention, and describes several embodiments, adaptations,
variations, alternatives and uses of the invention, including what
is presently believed to be the best mode of carrying out the
invention.
[0013] As used in this specification and the appended claims, the
singular forms "a," "an," and "the" include plural referents unless
the context clearly indicates otherwise. Also, the term "parallel"
is intended to mean "substantially parallel" and to encompass minor
deviations from parallel geometries. The term "perpendicular" is
intended to mean "perpendicular or substantially perpendicular" and
to encompass minor deviations from perpendicular geometries rather
than to require that any perpendicular arrangement described herein
be exactly perpendicular. The term "square" is intended to mean
"square or substantially square" and to encompass minor deviations
from square shapes, for example substantially square shapes having
chamfered (e.g., rounded or otherwise truncated) corners. The term
"rectangular" is intended to mean "rectangular or substantially
rectangular" and to encompass minor deviations from rectangular
shapes, for example substantially rectangular shapes having
chamfered (e.g., rounded or otherwise truncated) corners.
[0014] This specification discloses high-efficiency solar modules
(also referred to herein as solar panels) comprising silicon solar
cells arranged in an overlapping shingled manner and electrically
connected in series by conductive bonds between adjacent
overlapping solar cells to form super cells, with the super cells
arranged in physically parallel rows in the solar module. A super
cell may comprise any suitable number of solar cells. The super
cells may have lengths spanning essentially the full length or
width of the solar module, for example, or two or more super cells
may be arranged end-to-end in a row. This arrangement hides solar
cell-to-solar cell electrical interconnections and increases the
efficiency and the aesthetic attractiveness of the module.
[0015] Advantageously, the solar modules described herein include
electrical interconnects between rear surfaces of solar cells in
adjacent rows of super cells that provide alternative current paths
(i.e., detours) through the solar panel around damaged, shaded, or
otherwise underperforming solar cells. These detour current paths
do not pass through bypass diodes.
[0016] Turning now to the figures for a more detailed understanding
of the solar modules described in this specification, FIG. 1 shows
a cross-sectional view of a string of series-connected solar cells
10 arranged in a shingled manner with the ends of adjacent solar
cells overlapping and electrically connected to form a super cell
100. Each solar cell 10 comprises a semiconductor diode structure
and electrical contacts to the semiconductor diode structure by
which electric current generated in solar cell 10 when it is
illuminated by light may be provided to an external load.
[0017] In the examples described in this specification, each solar
cell 10 is a rectangular crystalline silicon solar cell having
front (sun side) surface and rear (shaded side) surface
metallization patterns providing electrical contact to opposite
sides of an n-p junction, the front surface metallization pattern
is disposed on a semiconductor layer of n-type conductivity, and
the rear surface metallization pattern is disposed on a
semiconductor layer of p-type conductivity. However, other material
systems, diode structures, physical dimensions, or electrical
contact arrangements may be used if suitable. For example, the
front (sun side) surface metallization pattern may be disposed on a
semiconductor layer of p-type conductivity, and the rear (shaded
side) surface metallization pattern disposed on a semiconductor
layer of n-type conductivity.
[0018] Rectangular solar cells 10 may be prepared, for example, by
separating a standard sized square or pseudo-square solar cell
wafer into two or more (i.e., N) rectangular solar cells each
having a length equal to the side length (e.g., 156 millimeters) of
the standard sized solar cell wafer and a width equal to a fraction
(i.e., about 1/N) of the side length of the standard sized solar
cell wafer. N may be, for example, 2 to 20 or more, for example 6
or 8.
[0019] Referring again to FIG. 1, in super cell 100 adjacent solar
cells 10 are conductively bonded directly to each other in the
region in which they overlap by an electrically conductive bonding
material that electrically connects the front surface metallization
pattern of one solar cell to the rear surface metallization pattern
of the adjacent solar cell. Suitable electrically conductive
bonding materials may include, for example, electrically conductive
adhesives and electrically conductive adhesive films and adhesive
tapes, and conventional solders.
[0020] FIG. 2 shows a front view of an example rectangular solar
module 200 comprising six rectangular super cells 100, each of
which has a length approximately equal to the length of the long
sides of the solar module. The super cells are arranged as six
parallel rows with their long sides oriented parallel to the long
sides of the module. A similarly configured solar module may
include more or fewer rows of such side-length super cells than
shown in this example. In other variations the super cells may each
have a length approximately equal to the length of a short side of
a rectangular solar module, and be arranged in parallel rows with
their long sides oriented parallel to the short sides of the
module. In yet other arrangements each row may comprise two or more
super cells, which may be electrically interconnected in series for
example. The modules may have shorts sides having a length, for
example, of about 1 meter and long sides having a length, for
example, of about 1.5 to about 2.0 meters. Any other suitable
shapes (e.g., square) and dimensions for the solar modules may also
be used. A super cell may comprise any suitable number of
rectangular solar cells of any suitable dimensions. Similarly, a
row of super cells may comprise any suitable number of rectangular
solar cells of any suitable dimensions arranged in one or more
super cells.
[0021] Solar modules as described herein typically comprise many
more (e.g., N times) as many solar cells as a conventional module
of the same size because N rectangular solar cells are formed from
a single conventional sized solar cell wafer. Optionally, the super
cells formed from these solar cells may be arranged in an
electrically parallel/series combination that provides current and
voltage outputs similar to those provided by a solar module of
about the same size comprising series-connected conventional size
solar cells. For example, if a conventional module includes M
conventional size solar cells electrically connected in series,
then a corresponding shingled super cell module comprising N
electrically parallel rows of super cells with each super cell row
comprising M series connected rectangular solar cells (each having
1/N the area of a conventional solar cell) would provide about the
same voltage and current output as the conventional module.
[0022] The example solar modules of FIG. 2 and of FIGS. 3-11
(described below) comprise six rows of super cells all of which are
electrically interconnected in parallel by terminal interconnects
250 at opposite ends of the rows. Because of the electrically
parallel arrangement, the voltage across each row (voltage between
one end of the row and the other) is the same though the current
through each row may be different. "Detour" electrical interconnect
arrangements similar to those described below with respect to FIGS.
3-11 may also be employed in solar modules comprising fewer rows of
super cells and/or in which some but not all rows of super cells
are electrically connected in parallel.
[0023] Typically, though not necessarily, the solar modules
described herein comprise one or more (e.g., three) bypass diodes.
If a solar cell arranged electrically in parallel with one of the
bypass diodes significantly limits current due to shading,
cracking, or otherwise suboptimal cell performance, the bypass
diode will become forward biased and electrically bypass that solar
cell or a portion of the module including that solar cell. This
prevents formation of a dangerous hot spot around the current
limiting cell and improves performance of the module.
[0024] Because the solar modules described herein include super
cells electrically connected in parallel, there is an opportunity
to improve performance further by providing alternate current paths
(i.e. detours) so that in the event that one cell in a super cell
is severely shaded or otherwise current limiting an adjacent string
of cells in an electrically parallel super cell can try to
compensate by operating at a higher current. These detour paths
pass through the rear surface metallization of solar cells and
through detour electrical interconnects that electrically connect
equal voltage pairs of solar cells located side-by-side in adjacent
super cell rows in the module. Conduction through the rear surface
metallization of the solar cells enable the bypass and detour
architectures using detour interconnects and/or planar patterned
metallized back sheets described herein.
[0025] In the extreme case all rows of super cells are electrically
connected in parallel and every solar cell would have detour
connectors attached to at least one cell in a different (e.g.,
adjacent) row to provide alternative current paths. However, detour
connectors can instead be placed on a subset of cells to
statistically reduce the likelihood that damage from cracking or
other failure mechanisms significantly degrades performance of the
module.
[0026] Furthermore, detour connections can be concentrated in areas
of the module most likely to experience cell cracking, such as for
example along well know stress lines from mechanical loading.
Cracks can be created by several mechanisms, may be dependent on
the way the module is mounted in the field or on the roof, and may
occur in predictable patterns based on the mounting method and the
source of stress. Wind and snow load create specific stress and
hence cracking. Walking on the module may create cracks. Severe
hail may create another type of crack. While initially cracks may
not cause electrical disconnects or otherwise degrade a module's
performance, the cracks may expand as the module goes though
heating and cooling cycles and eventually significantly affect
module performance. Cracks in monocrystalline and polycrystalline
cells may behave differently.
[0027] The detour electrical connections between the rear surface
metallization on solar cells in adjacent rows may be made, for
example, using short copper interconnects that bridge a gap between
the rows and that are conductively bonded at opposite ends to the
rear surfaces of the solar cells. The detour interconnects may be
bonded to the solar cells (e.g., to contact pads on the rear
surface of the solar cells) using solder or conductive glue or
other conductive adhesive, for example, or by any other suitable
method. Any portion of a detour interconnect that would otherwise
be visible from the front of the solar module (i.e., through a gap
between rows) may be covered with a black coating or black tape, or
otherwise darkened or hidden, to preserve an "all black" look from
a front view of the module. In operation, the conductive detour
current path may include portions of the rear surface (e.g.,
aluminum) cell metallization as well as the detour
interconnect.
[0028] Alternatively, the detour interconnections between solar
cells in a "line" of solar cells oriented perpendicularly to the
super cell rows may be made for example with a single long
approximately module-width crossing ribbon that is conductively
bonded to the rear surface of each cell in the line. This approach
may be preferred for example for modules including very large
numbers of solar cells, for example a module having six rows of
super cells with each row having eighty solar cells. Such a module
would otherwise require 400 separate short interconnects to provide
detour paths for each cell.
[0029] The detour interconnections (short or long) may be made in
the same way as "hidden tap" interconnections to bypass diodes, as
described for example in U.S. patent application Ser. No.
14/674,983 titled "Shingled Solar Cell Panel Employing Hidden Taps"
filed Mar. 31, 2015, which is incorporated herein by reference in
its entirety. The '983 application also discloses rear surface
metallization patterns and contact pads for hidden tap
interconnections to bypass diodes that facilitate detour
interconnections as described herein as well. As shown in FIGS.
3-11, for example, the detour paths and the connections to bypass
diodes in a solar module may be made using the same or
substantially similar types of interconnects.
[0030] The detour interconnections may also be made, for example,
using a patterned metallized back sheet conductively bonded to the
rear surfaces of the solar cells, with the patterned metallization
on the back sheet providing the detour current interconnections.
The patterned metallization on the back sheet may also provide
electrical connections to bypass diodes and/or to a junction box.
(See discussion of FIGS. 14A-14B below, for example). Typically,
the metallization pattern on the back sheet is single layer
planar.
[0031] In the example solar module 300 of FIG. 3, all available
detour paths are installed. That is, the rear surface metallization
of each solar cell 10 is electrically connected to the rear surface
metallization of its neighbor solar cell (or solar cells) in
adjacent super cell rows by detour interconnectors 275. Two of the
detour interconnections (275A and 275B) are also electrically
connected via return wires (conductors) 280A and 280B to three
bypass diodes (not shown) in junction box 290. Return wires 280C
and 280D electrically connect the bypass diodes to terminal
interconnects 250. The other detour interconnections in line across
the rows with detour interconnect 275A or 275B serve as hidden taps
to the bypass diodes in addition to providing detour current paths.
(Similar arrangements with detour interconnects also providing
hidden taps to bypass diodes are shown in other figures, as
well).
[0032] In FIG. 3 and the other figures described below, it should
be understood that return wires such as 280A-280D, for example, are
electrically insulated from the solar cells and conductors over
which they pass, except at their ends. For example, return wire
280B in FIG. 3 is electrically connected (e.g., conductively
bonded) to detour electrical interconnect 275B but electrically
insulated from the other detour electrical interconnects over which
it passes on the way to junction box 290. This may be accomplished
for example with a strip of insulation placed between the return
wire and the rear surfaces of the solar cells and other module
components.
[0033] The example solar module 400 of FIG. 4 is similar to that of
FIG. 3, except that in solar module 400 every other (i.e.,
alternating) solar cell along a super cell row has detours
installed.
[0034] In example solar module 500 of FIG. 5, detour interconnects
275 are installed in a pattern designed to compensate for a typical
crack pattern that may result from uniform mechanical loading of a
solar module. The crack pattern is shown in FIG. 13 superimposed on
a sketch of a conventional ribbon tabbed solar module, with the
crack pattern generally indicated by lines 305. In the example of
FIG. 5, conductors 280A and 280B are conductively bonded to the
rear surface metallization of solar cells 10A and 10B,
respectively, to electrically connect them to bypass diodes in
junction box 290
[0035] Detour interconnects may be installed at any suitable
intervals along a super cell row. The intervals may be equal or
approximately equal, or instead vary in length along the row. In
example solar modules 600 (FIG. 6) and 700 (FIG. 7), detour
interconnects 275 are installed in four approximately evenly spaced
lines across the module. In example solar modules 800 (FIG. 8) and
900 (FIG. 9), detour interconnects 275 are installed in five lines
across the module, with the interval between detour interconnects
greater at one end of the module than at the other end of the
module. In example solar module 1000 (FIG. 10), detour
interconnects 275 are installed in six lines across the module,
with the interval between interconnects greater in the central
portion of the module than at the ends of the module. In example
solar module 1100 (FIG. 11), detour interconnects 275 are installed
in nine lines across the module in combination with five
series-connected bypass diodes, with two lines of interconnects
between each adjacent pair of bypass diodes.
[0036] If the solar module comprises bypass diodes, any suitable
number of bypass diodes may be used and they may be spaced along
the super cell rows at any suitable interval. The bypass diodes may
be installed in a junction box, or alternatively embedded in a
laminate comprising the solar cells. Example solar modules 300,
400, 500, and 1000 each include three series-connected bypass
diodes (not shown) arranged in junction box 290. In example solar
modules 600, 700, 900, and 1100 five series-connected bypass diodes
310 are embedded in the solar cell laminate. In example solar cell
module 800 three series-connected bypass diodes 310 are embedded in
the laminate. Example solar modules 700 and 900 each include two
junction boxes 290A and 290B, one at each end of the module, each
providing a single (e.g., positive or negative) output.
[0037] Referring now to FIGS. 12A-12B, a crack (e.g., crack 330)
oriented along the long axis of a solar cell 10 can substantially
reduce current flow perpendicular to the long axis of the cell,
which is the direction in which current generally and preferably
flows through the solar cells during normal operation of the
modules described herein (i.e., when not taking a detour path). The
use of detour electrical interconnects as described above can
provide a detour path around the cracked cell.
[0038] A detour current path around and over the crack can also be
provided within the cell, as shown in FIGS. 12A-12B. In particular,
detour interconnect contact pads 320 on the rear surface of the
solar cell are positioned at the short ends of the solar cell and
elongated parallel to the short ends to substantially span the
width of the solar cell. Detour interconnects 275 that are
conductively bonded to these contact pads provide a crack jumping
current path, allowing current within the cell to make its way to
an interconnect 275, go over or around the crack, and then back to
the other part of the solar cell as shown for example by arrows
335.
[0039] Referring now to FIGS. 14A-14B, example patterned metallized
back sheet 350 provides detour current paths and electrical
connections to bypass diodes 310 in a junction box 290
corresponding to those provided by detour interconnects 275 and
return wires 280A-280D shown in FIG. 10. (The junction box is not
part of the back sheet, but is located in the module with respect
to the back sheet as shown in the figures). In particular, the
metallization pattern comprises a positive return region 355, a
negative return region 360, a first bypass diode return path 365, a
second bypass diode return path 370, two rows of detour
interconnect regions 375A that also serve as hidden taps to the
bypass diodes, and three additional rows of detour interconnect
regions 375B. Metallization is removed from the sheet, for example
as indicated at 380, to electrically isolate the various regions
from each other.
[0040] Although in the example solar modules described above each
rectangular solar cell 10 has long sides having a length equal to
the side length of a conventional silicon solar cell wafer,
alternatively the long sides of solar cells 10 can be a fraction
(e.g., 1/2, 1/3, 1/4, or less) of the side length of a conventional
solar cell wafer. The number of rows of super cells in a module can
be correspondingly increased, for example by the reciprocal of that
fraction (or by one or more rows less than the reciprocal to leave
room for gaps between rows). For example, each full length solar
cell 10 in solar module 300 (FIG. 3) could be replaced by two solar
cells of 1/2 length arranged in eleven or twelve rows of super
cells, or in any other suitable number of rows of super cells. The
rectangular solar cells could have dimensions of 1/6 by 1/2 the
side length of a conventional solar cell wafer, for example.
Reducing cell length in this manner may increase the robustness of
the cells with respect to cracking, and reduce the impact of a
cracked cell on performance of the module. Further, the use of
detour electrical interconnects or metallized backing sheets as
described above with smaller cells as just described can increase
the number of detour current paths available through the module
(compared to the use of full length cells), further reducing the
impact of a cracked cell on performance.
[0041] This disclosure is illustrative and not limiting. Further
modifications will be apparent to one skilled in the art in light
of this disclosure and are intended to fall within the scope of the
appended claims.
* * * * *